Cancer is a public health concern. Despite advances in treatments such as chemotherapy, the prognosis for many cancers, including hematological malignancies, may be poor. For example, it has been estimated that more than 45,000 deaths were expected from non-Hodgkin's lymphoma and leukemia in the United States in 2000 (Greenlee et al., CA Cancer J. Clin., 50:7-33 (2000)). Accordingly, there exists an unmet need for additional treatments for cancer, particularly hematological malignancies.